| 摘要 |
1. Monolithic integrated D/A converter comprising bipolar current-source transistors (Tq) whose base regions are jointly connected to a reference voltage (Ur) and whose emitter regions are each connected through an emitter resistor (Rq) to a forward-voltage source (-Up) and which consist in part of similar current-source transistor units and whose individual collector regions are connected to the emitters of a least one pair of bipolar switching transistors which serve to switch the currents of the individual current-source transistors (Tq) between ground potential (Uo) and the output (A) and consist in part of pairs of similar switching-transistor units, with - the base terminals of the first transistors (T1) of the switching-transistor pairs connected each to one of the bit lines (E), - the collector terminals of these first transistors connected jointly to ground potential (Uo), - the base terminals of the second transistors (T2) of the switching-transistor pairs connected jointly to the output of a voltage source (Ut), and - the collector terminals of the second transistors connected to the output (A) of the converter, characterized in that - the converter is divided into a first N-bit converter section (I) with weighted resistors and a second M-bit converter section (II) with weighted currents, in which second converter section (II) the collector terminals of the second transistors (T2') are all together connected directly to the output (A) of the converter, - in the first converter section (I), n resistors are connected in series between ground potential (Uo) and the output (A), the first of which (R1) has a value of Ro, while the other (R2-Rn) have the values Rn=2**n-2. Ro for n=2, and - each of the nodes of the n resistors (R1 ... Rn) is connected to the collector terminal of the second transistor (T2) of one of the switching-transistor pairs, while that terminal of the last resistor (Rn) located on the output side is connected to the output (A) directly and to the collector of the second transistor (T2) of the nth switching-transistor pair, so that the collectors of the second transistors (T2) in the first converter section (I), with the exception of that at the output end, are connected to the output (A) through at least one of the resistors R2 to Rn. |
